What is Plasma Arc Welding, How it is created , on which principle its works and its Application

What is Plasma Arc Welding

Plasma arc welding (PAW) is a type of arc welding that uses a plasma torch to create an arc between the workpiece and a consumable electrode. The plasma arc is a more focused and intense version of the electric arc used in other types of arc welding, and it is used to melt the filler metal and the workpiece together. In PAW, the plasma arc is formed by constricting the arc through a small nozzle, which increases the temperature of the plasma and makes it more effective at melting metal. The plasma arc is also shielded by a stream of inert gas, which helps to protect the weld from contamination and to stabilize the arc. PAW is often used for welding materials that are difficult to weld with other methods, such as aluminum, stainless steel, and high-temperature alloys. 

How plasma arc is created for welding ?

In plasma arc welding (PAW), the plasma arc is created by passing an electric current through a gas stream. To create the plasma arc, the following steps are typically followed:

• A power supply is used to generate a high-voltage, low-amperage electric current.
• The electric current is passed through a gas nozzle, which constricts the arc and increases the temperature of the plasma.
• The plasma arc is created when the electric current ionizes the gas, causing it to become a plasma. The plasma is a highly ionized gas that is made up of free electrons and positive ions.
• An electrode, typically made of tungsten, is placed in the center of the gas nozzle. The plasma arc is created between the electrode and the workpiece.
• A stream of inert gas, such as argon or helium, is used to shield the plasma arc and the weld pool from contamination. The inert gas also helps to stabilize the arc and improve the quality of the weld.

Principle of plasma arc welding

The principle of plasma arc welding (PAW) is based on the creation and maintenance of an electric arc between a consumable electrode and the workpiece. The electric arc is created by passing an electric current through a gas stream, which ionizes the gas and creates a plasma. The plasma is a highly ionized gas that is made up of free electrons and positive ions.

In PAW, the plasma arc is formed by constricting the arc through a small nozzle, which increases the temperature of the plasma and makes it more effective at melting metal. The plasma arc is also shielded by a stream of inert gas, which helps to protect the weld from contamination and to stabilize the arc.

The plasma arc is used to melt the filler metal and the workpiece together, forming a weld pool. As the weld pool cools, it solidifies and becomes the weld joint. The weld joint is typically stronger than the base metal, and it is used to join two or more pieces of metal together.

PAW is often used for welding materials that are difficult to weld with other methods, such as aluminum, stainless steel, and high-temperature alloys. It is also used for welding thin materials and in situations where precise control of the weld pool is required.

Application of plasma arc welding

Plasma arc welding (PAW) has a number of applications in various industries, including manufacturing, construction, and automotive. Some of the specific applications of PAW include:

1. Welding thin materials: PAW is often used for welding thin materials, such as sheet metal, because it provides precise control of the weld pool and produces high-quality welds.
2. Welding aluminum: PAW is well-suited for welding aluminum because it produces a narrow, concentrated arc that is effective at melting the metal.
3. Welding stainless steel: PAW is often used for welding stainless steel because it produces a high-quality weld that is resistant to corrosion.
4. Welding high-temperature alloys: PAW is used for welding high-temperature alloys, such as Inconel and Hastelloy, because it can produce a weld that can withstand high temperatures.
5. Welding in tight spaces: PAW is often used in situations where access to the weld joint is limited, such as in the corners of a weldment or in tight spaces between components.
6. Welding in automated systems: PAW can be used in automated welding systems, such as robotic welding cells, because it is a precise and reliable welding process.

There are several advantages of plasma arc welding:

1. High welding speed: Plasma arc welding is a fast welding process that can produce high-quality welds in a relatively short period of time.
2. High precision: Plasma arc welding is a precise welding process that allows for tight control of the weld bead and minimal distortion of the workpiece.
3. Versatility: Plasma arc welding is a versatile welding process that can be used on a wide range of materials, including steel, aluminum, copper, and titanium.
4. Energy efficiency: Plasma arc welding is an energy-efficient welding process that uses a smaller amount of energy than other welding processes.

There are also some disadvantages of plasma arc welding:

1. High cost: Plasma arc welding equipment is relatively expensive, which can make it cost-prohibitive for some applications.
2. Specialized training: Plasma arc welding requires specialized training and expertise, which can be a barrier to entry for some individuals.
3. Health and safety concerns: Plasma arc welding generates high temperatures and intense ultraviolet (UV) and infrared (IR) radiation, which can pose health and safety risks to the operator if proper precautions are not taken.
4. Limited thickness capacity: Plasma arc welding is limited in the thickness of materials it can weld, which can limit its effectiveness in certain applications.